shared pool running out of memory

Hello expert,

                     Recently in one of the database we were hitinh ora-4031 as shared pool was running out of memory.We flushed shared pool and after that issue got resolved.We understand sga needs to be increased but can't understand how much we have to and what will be the benefit?Please suggest us.

SQL> SELECT parameter, oper_type, oper_mode, initial_size, target_size, status, start_time, end_time FROM v$sga_resize_ops
  2  where trunc(start_time)=trunc(sysdate);

PARAMETER                      OPER_TYPE     OPER_MODE INITIAL_SIZE TARGET_SIZE STATUS    START_TIME        END_TIME
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